Cellulose solutions and process for their production



eaanaa July 29, 1930 UNITED STATES LEON LILIENFELD, OF VIENNA, AUSTRIA CELLULOSE SOLUTIONS AND PROCESS FOR THEIR PRODUCTIOLl' No Drawing. Original application filed May 10, 1924, Serial No. 712,475,.and in Austria June 5, 1923. Divided and this application filed February 15, 1928. Serial No. 254,625.

I have discovered that strong organic bases, particularly quaternary ammonium bases or those bases in the aqueous solution of which a highly electrolytic dissociated hydroxide is assumed to be present or mixtures of substances which are capable of forming strong organic bases, exercise a solvent action on cellulose, its conversion products and its oxidation products. This 10 solvent action of strong organic bases is enhanced in presence of alkali.

My invention relates to a process for making cellulose solutions based on the foregoing discovery.

' The fact that strong organic bases, particularly quaternary ammonium bases or those bases in the aqueous solutions of which a highly electrolytic dissociated hydroxide is assumed to be present, have a dissolving efiect on cellulose or its conversion products,

is not only surprising in itself. It must be, described as entirely unexpected, that the solvent action of these bases even exceeds that of caustic alkalies, so far as such action exists. The more powerful solvent action of the strong organic -bases is evident from the fact, for example, that whereas caustic alkali solutions are able to dissolve mercerized cellulose or bleached cellulose or bleached and mercerized cellulose'or certain cellulose conversion products 'obtained from cellulose solutions, such as the cellulose hydrate regenerated from viscose, including viscose silk, or the cellulose conversion prod-.

not obtainable from ammoniacal solutions of cupric oxide by precipitation, including copper silk and the like, only at low. temperatures, such bodies from the cellulose group aredissolved even at room tempera- 40 ture inaqueous solutions of strong organic bases, for example a solution'of 20 to per cent. strength of tetraethylammoniumhydroxide or tetramethylammoniumhydroxide or phenyltrimethylammoniumhy- 4 droxide. .Thus, according to the particular nature ofthe body from the cellulose group to be dissolved, the solvent action of the strong organic bases or of their aqueous solutions, in presence or absence of alkalies, 5 takes effect either at room temperature or at a higher temperature or at a temperature between room temperature and 0, or only below 0.

Thus, for example, those conversion products which may be obtained by separation from solutions of cellulose-in suitable solvents (for example strong miner 1 acid, ammoniacal cupric .oxide, zinc o loride) or from viscose, dissolve in suitable bases, or aqueous solutions thereof in presence or. absence of alkali even at room temperature. Mercerized cellulose or bleached cellulose or bleached and mercerized cellulose, according to the degree of mercerizing or bleaching, dissolves either at room temperature or between room temperature and 0 or not very far below 0, whereas slightly disintegrated or not disintegratedcellulose dissolves only below 0 in the bases or aqueous solutions thereof in presence or absence of alkalies. In

every caseit is easy to determine the proper temperature by a simple preliminary test, namely by mixing the cellulosic .body with the desired base or solution thereof in water alone or in presence of alkali and, if no solution occurs at room temperature, cooling by stages until a solution is produced.

Hereinafter the conduct of the process is described and illustrated by examples. It is, however, expressly emphasized that it is not intended to limit the invention to the details of this description.

As parent materials for the present process the following may be named by way of example:

(1) Bleached or unbleached cellulose of every kind and in every form inw'hich it is available;

lose;

(3) Those conversion products which are formed by mechanical comminution (for example. grinding or shredding) of the cellulose in'prcsence of'water;

(4) Cellulose conversion products or oxidation products obtained by treating cellulose or its conversion products with oxidizing or reducing bleaching agents of every kind, irrespective of whether preliminary treatment (for example with alkalies, acids,

(2) Every kind of matter containing cellusalts or the like) has or has not preceded the bleaching operation;

(5) The conversion products obtained by heating cellulose alone or in presence of water or glycerine or the like at normal, reduced or increased pressure;

. (6) The cellulose conversion zproducts made by treating cellulose or-its conversion products with caustic alkali solutiOns'and, Where necessary, removing the excess alkah solution by pressing, centrifuging or the like (mercerizing the cellulose), with or withsion products by suitable precipitating agents or other means and, if desired, purified by washing; for example from solutions or pastes of cellulose or cellulose hydrates or hydrocelluloscs in ammoniacal cupric oxide or in any other solvent containing copper as a basis, or from solutions or pastes of cellu lose or cellulose hydrates or hydro-celluloses in zinc halides, for example zinc chloride alone or in presence of an acid or a salt, or from solutions or pastes of cellulose or cellulose hydrates or hydro-celluloses in strong mineral acids, such as sulphuric acid, phosphoric acid, hydrochloric acid, arsenic acid and the like alone or-mixedwith each other -or in admixture with other inorganic or organic ,acids or acid salts, or from crude or purified viscoses (cellulose xanthates) when decomposed spontaneously or by other means. Of all the cellulose conversion products separated from cellulose solutions the statement holds good that the nature of the precipitating agent is without influence on the present process;

(9). Artificialthreads and yarns of every kind consisting of, or containing cellulose or cellulose hydrate or degraded cellulose, i. e. hydro-cellulose or oxy-cellulose, such as artificial threads made from viscose (for example viscose silk or viscose staple fibre of viscoseartificial wool) or from solutions of cellulose in cuprammonia or denitrated' cellulose ni.

trate-silk or saponified cellulose acetate silk and the like; 1

(10) Cellulose conversion products which are obtained by treating, short of dissolution, cellulose or its conversion prdducts (such as cellulose hydrates or hydro-celluloses) with solvents, such as strong mineral acids (for example parchmentizing acid) or zinc halides (for example zinc chloride or the like) or ammonical cupric oxide;

(11) Hydro-cellulose of every kind, such as are obtained, for example, by treating bleached or unbleached cellulose With dilute acids in the cold or at a raised temperature under ordinary or increased pressure or by drying .in presence of acids or by treating j cellulose with strong sulphuric acid of specific gravity lower than 50 Baum in the cold, gaseous hydrochloric acid or chlorine;

(12) Oxy-celluloses of every kind;

(13) The cellulose conversion product obtainable from cellulose derivatives, such as esters or the like by scission of the molecule or bysaponification, for example denitrated cellulose nitrate or saponified cellulose acetate or formate or the like.

The aforesaid conversion or oxidation products may be used in the dry, air-dry, moist or Wet state. Inthe last two cases the percentage of water in the parent material must be takenv into account when determining the strength and proportion of the solution of the base intended for the dissolution; In the succeeding portion of the description and in the claims, wheresoever the meaning admits, the expression body of thecellulose .group or parent material is intended to include allthe materials enumerated in the foregoing paragraph, and the expression cellulose conversion product is intendedto comprise all the materials designated imparts (3) to (13), both inclusive, of the foregoing paragraph.

' The conduct of the process is simple. It consists substantially in treating the body of thecellulose group with a preferably aqueous solution of a strong organic base, for example a quaternary ammonium base or a base in the aqueous solution of which a highly electrolyti- I cally dissociated hydroxide is assumed to be present or two or more such bases, in presence or absence of caustic alkali, preferably while stirring, at a temperature suitable for dissolving the cellulosic body concerned, until dissolution occurs. Instead of the base itself,

there may be used mixtures of such substances as are capable of forming the base in question or substances capable of conversion with formation of thebasein question.

If dissolution is effected while cooling, it

is conducted preferably in a vessel adapted to be cooled either externally or internally or bothexternally and internally and having in addition a mixing, kneading or stirring dev1ce.

The solutions of the bodies from the cellulose group obtained according to the present process, if desired after previous filtering or straining or centrifuging may be used for making technical products, such as artie ficial threads or yarns (for example artificial silk, artificial cotton, staple fibre or the like) artificial hair, films of every kind, plastic masses, coatings of every kind upon paper,-

textiles, "leather and the like, finishings and fillings for fabrics, sizing for yarns, book cloth, artificial leather and the like.

The solutions are easily worked up into technical products, since they are readily coagulated by suitable precipitating baths, such as inorganic or organic acids, salts, alcohols, in some cases even water, or by heat, steam and the like. 1

The following examples illustrate the invention, the parts being by weight?- I. For this example there are used parts or (if the parent material contains water) a proportion corresponding with 10 parts of the parent material of any of the following parent materials: r

(1) Finely subdivided sulphite-cellulose; (2) Bleached cotton, for example in the form of medicated cotton-wool; f

(3) Mercerized cellulose produced, for example in the following manner. 100 parts of sulphite-cellulose in fleece or sheet form or medicated cotton wool are impregnated with 900 to 1000 parts of a caustic soda solution of 18 to percent. strength of room temperature; the mass is left in the caustic soda solution for 6 up to 2 1 hours and then immediately washed or is first pressed or centrifuged until it weighs 200 to 300 parts and shredded or comminuted in a suitable apparatus (for example shredder, beater, willowing machine or the like) and, either directly after comminution or after standing for 1 up to 3 days at room temperature,- Washed with cold or hot water. The washed,

mercerized cellulose is then pressed or centrifuged-and dried in a vacuum or in the air or used in the centrifuged orpressed state, where 2 desirable after previous comminution.

(4) Cellulose comminuted or ground in presence of water and produced, for example in the following manner 1 200'parts of sulphite-cellulose in fleece or sheet form are stirred-with 10 to 20 times their weight of water until the-mixture is homogeneous, and after standing for several hours or several days at room temperature 1t is pressed or centrifuged until it weights 250v.

to 350 parts. The residue is ground or comminuted for several hours up to 8 days in a suitable apparatus (for example shredder, beater,. willowing machine, kneading machine or the like) and, if desired dried.

' (5) Cellulose previously treated with di-' lute mineral acids, for example according to the following directions :100 parts of bleached,or unbleached.sulphite-cellulose are boiled with 1000' to 4000 parts of hydrochloric acid 0fper cent, strength in an open vessel for up to 3 hours, then, if desired, after previous pressing or centrifuging, the product is washed and pressed or centrifuged and, if desired, dried.

' (6) Viscose silk or copper silk or waste of Such silks.

(7 Cellulose hydrate obtained by precipitating or treating viscose in the dissolved or undissolved state (that is to say, sulphidized alkali cellulose before its dissolution) with a dilute mineral-acid, for example sulphuric acid of 5 per cent.- strength, washing the precipitate and, if desired, drying.

(8) Cellulose conversion products obtained by dissolving cellulose in strong sul while kneading or mixing and continuously cooling. The-introduction occupies about 20 .minutes. Thetemperature of the mass is kept at about 10 to 11 C., during the introduction. After the whole of the sulphite-cellulose is incorporated in the'sulphuric acid, the product is a tough dough which may be rolled out on a glass plate and,

in a thin layer, appears transparent. This dough is continuously cooled to 10 (1., to 12 (3., while kneading for another to 1 hour, and is then kneaded with ice water, added in small portions, until it is entirely broken up. The roduct (if desired-after previous pressing of the purpose of recovering the sulphuric acid) is, washedwith water until sulphuric acid can'no longer be detected in the washing water and-until a test, portion of the body itself, boiled with water, yields'no more sulphuric acid tothe water. To accelerate the washing operation, the more or less coarse product may be triturated or ground in the moist state once orseveral times during the washing. The washedbody solution of tetramethylammoniumhydroxide or tetraethylammoniumhydroxide or phenyltrimethylammoniumhydroxide of such con centration, that the mixture contains 10 parts of'air-dry parent material and 190 to 240 to 50 per cent. strength, whereupon the mass is stirred at room temperature until it ,is homogeneous.

The result in the case of parent material 1, 2, '3 and tis merely a more or less appreciable swelling, whereas in the case of parentmaterials 5, 6, 7 and 8 dissolution occurs to a considerable extent.

Then, preferably while stirring or kneading, the mass is cooled to -8 to 11 (1, and kept at. this temperature for some seeonds up to 30 minutes.

Under the action of the cold dissolution parts of a solution of one of these bases of 20 occurs in the first four cases; in the last four improvement, that is to say completion of the solution already'begun. The solutions are viscous, but liquid, and may be freed from any undissolved constituents that may be present by straining, filtering or centrifugmg. I

Spread in thinlayers on glass plates and treated with a-suitable precipitating bath (for example dilute sulphuric acid), th se solutions yield films which are transparent and flexible after washing and drying. They may also be worked up into artificial threads, such as artificial silk, by spinning into suitable precipitating baths (for example dilute sulphuric acid or dilute sulphuric acid in admixture with a salt).

II. The mode of operation is as in example I, except that for dissolving the 10 parts of the parent material there are used 190 to 240 parts of a solution of 10 to 30 per cent. strength of tetramethylammoniumhydroxide or tetraethylammoniumhydroxide or phenyltrimethylammoniumhydroxide in soda solution'of 5 to 10 per cent. strength.

The presencefof the caustic'soda enhances the solvent action of the bases. For the rest, the result is'roughly as in Example I. J

This case-is a division of my application Serial No. 712,47 5, filed May 10, 1924.

Having described my" invention what I claimisp 1. The process of making cellulosic solutions which comprises treating a body of the a strong organic base.

2. The process of making' cellulosic solutions which comprises treating a body of the cellulose group in an undissolved state with a strong organic base at a low temperature.

3. The process of making cellulosic solu tions which comprises treating a body of the cellulose group in an undissolved state with an aqueous mixture containing a. strong organic base.

4. The process of making cellulosic solucellulose group in an undissolved state with tions which comprises treating a body of the body of the cellulose group which comprises treating the said body in an undissolved state.

cellulose group in an undissolved state-with aliquid containing 'a strong organlc base.

caustic body of the cellulose group which comprises treating the said body with a'liquid comprising a quaternary ammonium hydroxide.

9. The process of forming a cellulosic solution which compr ses treating a water insoluble cellulosic body-with a strong organic base.

10. The process of forming a cellulosic solution which comprises treating a water insoluble cellulosic body with a strong organic base at a low temperature.

11. The process of forming a cellulosic solution which com rises treating a water insoluble cellulosic 'ody with an aqueous mixture including a strong organic base. Q

. 12. The process of forming a cellulosic solution which comprises treating a water insoluble cellulosic body with an aqueous mixture including a strong organic base at a low temperature.

13. The process of forming a cellulosic solution which comprises treating a water insoluble cellulosic body with a quaternary ammonium hydroxide.

14:. The process of forming a cellulosic solution which comprises treating a water insoluble cellulosic body with a quaternary ammonium hydroxide at a low temperature.

15. The process of forming a celluloslc solution which comprises treating awater insoluble cellulosic body with an aqueous mixture containing a quaternary ammonium hydroxide.

16. A solution of a water insoluble cellulosic body in a strong organic base.

' 17. A solution of a water insoluble cellw losic body in an aqueous mixture containing a strong organic base.-

18. A solution of a body of thecellulose.

group in a quaternary ammonium hydroxide.

19. A solution of a body of the cellulose group in an aqueous mixture including a. quaternary ammonium hydroxide.

20. A solution of a body of the cellulose grou" in an aqueous mixture containing quate nary ammonium hydroxide and alkali hydroxide.

In testimony whereof I afiix my signature.

DR. LEON LILIENFELD.

5. The process of forming a solution of a' with a quaternary ammonium hydroxide.

. the presence of an alkali.

6. The process offorining a solution of a body of the cellulose group which comprises treating the said body in an undissolved state with a quaternary ammonium hydroxide in i 7 7. The process of forming a solutionof a bodyof the cellulose group which comprises treating the said body with a quaternary ammonium hydroxide in .the presence of an aqueous solution of hydroxide ofan alkali metal. a 1

8. The process of forming a solution of a 

